IP1.29.4 Frequency and pitch © Oxford University Press 2011 Frequency and pitch.

transcript

IP1.29.4 Frequency and pitch

Frequency and pitch

The higher the frequency of a sound wave, the higher its pitch. A high pitched sound has high frequency.

Higher pitch

Pitch and frequency

Lower pitch

The greater the amplitude of a sound wave the louder the volume. A loud sound has high amplitude.

Louder

Volume and amplitude

Quieter

Humans can hear sounds in the range of 20 to 20 000 Hz. Sound waves above this frequency are called ultrasound and below this frequency are called infrasound.

Infrasound Ultrasound

Below 20 Hz 20 Hz to 20 000 Hz Above 20 000 Hz

Human hearing

Different animals can hear a range of different frequencies of sound. The frequency of a dog whistle is too high-pitched for humans to hear.

A special piece of equipment called an oscilloscope can be used to produce a picture of a sound wave.

If the sound increases in pitch, the waves get closer on the oscilloscope screen. Their frequency has increased.

IP1.29.4 Frequency and pitch © Oxford University Press 2011 Frequency and pitch.

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